Thermally tuned reflex klystron



May 14, 1963 T. D. FENTRESS, JR., ETAL 3,089,976 THERMALLY TUNED REFLEXKLYSTRON Filed April 14, 1960 INVENTORS 7:0. FENTRESSIR. we. SHEPHERD BYGE. WURIHMANN ATTORNEY United States Patent 3,089,976 THERMALLY TUNEDREFLEX KLYSTRON Thomas Dawley Fentress, Jr., Eatontown, N.J., WilliamGerald Shepherd, St. Paul, Minn., and Gunther Ernest Wurthmann, RedBank, N.J., assignors to The Bendix Corporation, a corporation ofDelaware Filed Apr. 14, 1960, Ser. No. 22,235 3 Claims. (Cl. 315-523)The present invention relates to electron discharge devices and moreparticularly to reflex oscillators of the cavity resonator type.

In reflex oscillators of the klystron type, due to operation at veryhigh frequencies, the dimensions of the critical components are ofnecessity small in physical size. Further, as the frequency is raised,the components become smaller in size. If an attempt is made tothermally tune a reflex klystron at very high frequencies by means of aconventional diode type tuner, the small size of the resonant cavity solimits the size of the tuning diaphragm that it is diflicult to achievethe compliance and movement required to cover the desired frequencyrange without making the diaphragm extremely thin and fragile.

The present invention provides a novel thermally tuned device in whichtwo diaphragms or flexible members are utilized. One of the diaphragrnsis relatively large in diameter and is located outside of the resonantcavity.

It is an object of the present invention to provide an improved electrondischarge device.

Another object of the invention is to provide an improved reflexoscillator.

Another object of the invention is to provide an improved =klystron.

Another object of the invention is to provide an improved thermallytuned klystron.

Another object of the invention is to provide novel means for thermallytuning a reflex oscillator of the cavity resonator type.

Another object of the invention is to provide a novel diode tuner for aklystron.

The above and other objects and features of the invention will appearmore fully hereinafter from a consideration of the following descriptiontaken in connection with the accompanying drawing, wherein oneembodiment of the invention is illustrated by way of example.

In the drawing, the single FIGURE is a cutaway section of a deviceembodying the invention.

Referring now to the drawing wherein an electron discharge device isindicated generally by the numeral 1, which may, for purposes ofillustration, be a klystron of the reflex type. The device 1 has anenvelope 2 which may be of the conventional type and is merely shown bydashed lines. Enclosed in the envelope 2 is a plate 3 of metal which hasa circular opening 4 defining a part of a cavity resonator. A slot orcut-out portion 5 extends from the opening 4 and defines a wave-guideoutput section for the device. A choke joint 6 is provided to minimizeloss of energy propagated through the wave guide 5 and a window 7mounted in the envelope 2.

A=flixed to one face of the plate 3 is a circular, metallic frame orsupport 8 having a frusto-conical portion 9 upon which is mounted a grid10 which may be of fine wire. An annular metallic diaphragm 11 issecured to the other face of the plate 3 and may be provided withconcentric corrugations 12. The diaphragm 11 carries a grid 13 which isconcentric with the grid 10.

Cooperatively associated with the cavity resonator, are an electron gun14 and a repeller electrode 15 to constitute a reflex oscillatortherewith. The electron gun 14 includes a cathode 16 and focusingelectrode 17. The gun 14 is secured to the block 3 by means of aninsulating ring 18 and flanged cylinder 19. An accelerating grid 20 maybe provided between the cathode 14 and grid 10.

The plate 3 has an axially extending flange 21 which supports a tunerfocusing electrode 22 on an insulating washer 23. A top plate 24 is alsosupported by the plate 3 and clamps the electrode 22, washer 23 andinsulating member 25 therebetween. The top plate 21 may have a pluralityof openings 26 to aid in the evacuation of the device. The repellerelectrode 15 extends through an opening 27 in the top plate 24 and issupported therein by an insulating collar 28, insulating washer 29,spacer 30 and nut 31. A repeller electrode shield 32 is secured by thecollar 28 and spacer 30.

A ring-like cathode 33 is positioned in the space between the tunerfocusing electrode 22 and repeller electrode shield by metal tabs 34.The cathode 33 is of the conventional type and includes a heater 35. Adiaphragm 36, which serves as the anode for the tuner diode, issupported at the outer edge on a step 37 on the plate 3 and has anopening 38 therein concentric with the grid 13. The diaphragm 36 isconnected to the diaphragm 11 by a ring 39 to which the two diaphragmsare brazed. The diaphragm 36 is of a stubstantially larger diameter thanthe diaphragm 11 and by virtue of its size it possesses the necessarycompliance to yield the desired motion, using thermal means, withoutbeing so fragile as to move by mechanical environments. The diaphragm 36is of a material having good thermal expansion characteristics togetherwith good creep strength, for example, a stainless steel known asCarpenter 347.

In operation, the diaphragm 36 serves as the anode of a diode tuner andis moved by thermal expansion caused by heating resulting from thecollection of current from the cathode 33. This motion causes thediaphragm 36 to move the diaphragm 11 to change the grid spacing of theresonant cavity with a corresponding change in frequency.

The connections to the various elements in the device have been omittedfor simplicity, however, it is understood that they would be made in aconventional manner.

Although only one embodiment of the invention has been illustrated anddescribed, various changes in the form and relative arrangement of theparts, which will now appear to those skilled in the art, maybe madewithout departing from the scope of the invention.

What is claimed is:

1. A reflex klystron comprising an envelope enclosing a resonant cavity,a fixed grid, a movable grid, a first diaphragm for mounting saidmovable grid in one wall of said cavity, a second diaphragm memberconcentric with said first diaphragm and positioned external of saidcavity, means for connecting said diaphragms together, and meansincluding a cathode for causing a thermal change in said seconddiaphragm thereby to tune said cavity.

2. A thermal tuned reflex klystron comprising a resonant cavity, a fixedgrid mounted in one wall of said cavity, a movable grid, means includinga flexible memsaid second flexible member is of a material having a highthermal coefi'icient of expansion.

References Cited in the file of this patent UNITED STATES PATENTSClifford et a1 Nov. 23, 1948 La Rue Dec. 9, 1952 Gardner Mar. 10, 1953Svensson Ian. 15, 1957

1. A REFLEX KLYSTRON COMPRISING AN ENVELOPE ENCLOSING A RESONANT CAVITY, A FIXED GRID, A MOVABLE GRID, A FIRST DIAPHRAGM FOR MOUNTING SAID MOVABLE GRID IN ONE WALL OF SAID CAVITY, A SECOND DIAPHRAGM MEMBER CONCENTRIC WITH SAID FIRST DIAPHRAGM AND POSITIONED EXTERNAL OF SAID CAVITY, MEANS FOR CONNECTING SAID DISPHRAGMS TOGETHER, AND MEANS INCLUDING A CATHODE FOR CAUSING A THERMAL CHANGE IN SAID SECOND DIAPHRAGM THEREBY TO TUNE SAID CAVITY. 